The present invention relates generally to semiconductor processing. More particularly, the present invention relates to a method for forming a dual damascene pattern.
As the semiconductor industry develops Ultra Large Scale Integration (ULSI) devices, reducing a device to a sub-half-micron size increases the circuit density, thereby causing a resistance-capacitance (RC) delay and copper reactive ion etching (RIE). In a process for forming a bit line pattern for devices of a reduced size, the pattern may be bridged or collapsed.
In order to prevent bridging and/or collapsing of the pattern and to improve the layout of the device, a dual damascene process has been developed. The dual damascene process can be used when it is impossible to pattern a metal material by a conventional etching technology due to the reduction of the device size, or it is difficult to fill a low dielectric material in a deep contact etching process for forming a conventional metal line.
By the dual damascene process, a contact line structure is formed. The contact line structure may include an aluminum metal line and an oxide film. Alternatively, the contact line structure may include a copper metal line and a low dielectric constant (low-k) material for reducing the RC delay in a LSI process.
Instead of a deposition structure including polysilicon, tungsten, a nitride film, and an oxide film as a hard mask, a deposition structure including an insulating film and an amorphous carbon layer is used in an etching process for forming a pattern of below 80 nm for semiconductor devices of a smaller size. The deposition structure secures an etching selectivity to a lower layer and has a faster etching speed than that of a photoresist and an antireflection film.
However, a process using the insulating film/amorphous carbon layer is complicated. In addition, the manufacturing cost is high, because a chemical vapor deposition (CVD) process is involved.
Recently, a multi-functional hard mask film, which serves as an organic anti-reflection film and a hard mask film, is developed to simplify the process.